For railway and the like which are positioned to compete with the other modes of transport, the cutback on travel time to reach the destination through speedup is a matter of vital interest. Railway speedup, however, presupposes a general level up in all the technologies of rolling stock, track, current collection and environment.
Since its reorganization the RTRI aspires for speedup taking speedup as one of the main pillars in its R & D activities, with its capabilities mobilized across the boundaries in a specialized group of speedup laboratory, high-speed, low-noise Shinkansen development division, narrow-gauge line speedup promotion division and speedup project team. Here are to be introduced the latest developments in Japan of railway speedup and the role being played by the RTRI.
Referring to the Shinkansen, upon completion of the Shinkansen vehicle Series 300 in 1992 a regular operation of trains at 270km/h against the conventional speeds of 220 - 240km/h was started. In the meantime, STAR 21, WIN 350 and 300X, which are experimental superspeed vehicles, were built with a fresh look and enhanced capacity and using them the testing of operation at a commercial speed in the order of 300km/h was launched to clear the environmental problems. In a series of high-speed runs in 1996, 300X marked the highest speed of 443km/h in Japan. On the other hand, JR West Japan successfully developed the Shinkansen vehicle Series 500 embodying the technologies so far achieved and, beginning March 1997, it opened the first commercial operation at 300km/h in Japan.
Meanwhile, the commercial operation on the narrow-gauge lines is pegged at 130km/h under the restraint of the emergency brake distance limited below 600m. Nevertheless, the 130km/h operating zone is expanding. In the case of narrow-gauge lines, to raise the curve or turnout passing speed would be more effective for general speedup than to raise the maximum speed on the tangent section of the line. It is for this reason that introduction of "controlled tilt train" on major lines is encouraged. In order to avoid an increased wear of wheel flange or rail edge as the running speed on the curve is raised, practical implementation of steering bogie is promoted.
As stated above, the advance in speedup on both Shinkansen and narrow-gauge lines owes very much to the stepped-up efforts done for better performance of running gear, implementation of inductive motor drive system, better performance of braking system, improvement of technologies for weight reduction of rolling stock and environmental measures to suppress noise and ground vibrations. From this viewpoint, the RTRI, stressing the importance of such technologies, has contributed substantially to the railway speedup.
To mention some examples, the RTRI has developed a high-performance, lightweight bolsterless bogie intended for Shinkansen vehicle which is widely adopted as standard component of the latest Shinkansen vehicles including series 300. Also the RTRI has come up with various proposals aimed to farther improve the running performance of the bolsterless bogie for Shinkansen vehicle and thereby increase the margin to safety in high-speed running, such as ;
- extension of truck wheelbase from the present 2500mm to 3000mm;
- replacement of the flanged cylindrical roller bearing with the conical roller bearing to narrow the axial clearance in the axle bearing; and
- utmost reduction of the unsprung mass and the inter-spring mass of the truck.
These ideas have been realized in the experimental 300X vehicle of JR Tokai and in the Shinkansen vehicle series 500 of JR West Japan.
Referring to the enhancement of ride comfort, what is currently attracting public attention is carbody vibration due to the aerodynamic disturbance generated by passing each other of high-speed Shinkansen trains in a long tunnel. In a bid to suppress such phenomena, the RTRI has developed and successfully implemented a semi-active (variable damping) damper and an anti-yaw-damper to be installed between carbodies.
In these achievements the role played as an important research tool by the vehicle test stand capable of testing the high-speed running stability of the truck and its anti-vibration as well as the simulation technologies should be duly appreciated. It should be noted that credit goes to this test stand for much of theoretical studies executed on it to verify the above-mentioned achievements. In recent times the technological requirements for speedup on the Shinkansen and narrow-gauge lines are increasingly sophisticated and they must be satisfied by a complex of different techniques. Against this background, the RTRI lately expanded the test facilities with new additions such as braking test device and large-size low-noise wind tunnel, which are expected to provide a powerful support for speed up research in future.